In the b2 tools environment when editing form fields the editor was in ascii-mode, now in c4 the editor is in gui-mode. That is not the problem, however the <next> and <previous> choices have been disabled and that makes editing forms/reports more difficult.

That's true
Actually, it wasn't just c4, the original had the buttons not greyed out and they worked. Some porting set took this away. You can still run ASCII for c4 - if you do you can probably see that it is a disabled option in ASCII mode as well now.